The present invention relates to a surveillance system for surveilling an image taken or image-picked up by, for example, a surveillance camera and more particularly, to surveillance system and method for detecting an intruder.
For example, in hotels, convenience stores, financial agencies or commercial and public facilities such as dams, railroads and thoroughfares, an image surveillance system has hitherto been installed with the aim of assuring crime deterrent and accident prevention.
In the image surveillance system, an object to be surveilled is picked up with an imaging device such as a camera and its image is transmitted to a surveillance center such as a guardian office or a janitor room so than a stationary surveillant may watch the image to provoke the warning as necessary or record/save the image.
Also, a technique called image recognition, for example, has been known according to which an image is digitized and the existence or movement of an object pictured on the image is identified from brightness or color information each pixel of the image has or from its time series change or distribution. Then, as the CPU (central processing unit) advances in its performance, the range of such an object as to be recognizable through the technique as above expands and recently, recognition can be promoted to such an extent that objects including humans, dogs, cats and cars and even a personal face as well can be recognized.
Further, JP-A-2005-143016 discloses a technique of counting the number of persons (visitors) inside a surveillance area of a shop, for instance.
Furthermore, an intruder detection system has been studied as an application of the aforementioned image recognition technique to the image surveillance system described above.
In the intruder detection system, intrusion of a person into a preset surveillance area is detected through the image recognition technique to inform a surveillant of the intrusion or to warn the intruder, thereby alleviating the burden imposed on the surveillant or deterring the intruder from committing an intrusion.